diff --git a/AppKitExtras/Sources/AppKitExtras/UserApp.swift b/AppKitExtras/Sources/AppKitExtras/UserApp.swift
index 39de0624b..1c205094e 100644
--- a/AppKitExtras/Sources/AppKitExtras/UserApp.swift
+++ b/AppKitExtras/Sources/AppKitExtras/UserApp.swift
@@ -12,7 +12,7 @@ import AppKit
 ///
 /// The app may or may not be running. It may or may not exist.
 
-public final class UserApp {
+@MainActor public final class UserApp {
 
 	public let bundleID: String
 	public var icon: NSImage? = nil
diff --git a/Core/Sources/Core/SendToCommand.swift b/Core/Sources/Core/SendToCommand.swift
index c60c6027d..24254bcea 100644
--- a/Core/Sources/Core/SendToCommand.swift
+++ b/Core/Sources/Core/SendToCommand.swift
@@ -37,7 +37,7 @@ public protocol SendToCommand {
 	///   - object: The object to test.
 	///   - selectedText: The currently selected text.
 	/// - Returns: `true` if the object can be sent, `false` otherwise.
-	func canSendObject(_ object: Any?, selectedText: String?) -> Bool
+	@MainActor func canSendObject(_ object: Any?, selectedText: String?) -> Bool
 
 	/// Send an object to the target application.
 	///
diff --git a/Mac/MainWindow/SharingServicePickerDelegate.swift b/Mac/MainWindow/SharingServicePickerDelegate.swift
index bbe3b0d4f..0701b1e11 100644
--- a/Mac/MainWindow/SharingServicePickerDelegate.swift
+++ b/Mac/MainWindow/SharingServicePickerDelegate.swift
@@ -18,15 +18,18 @@ import Core
 	}
 	
 	func sharingServicePicker(_ sharingServicePicker: NSSharingServicePicker, sharingServicesForItems items: [Any], proposedSharingServices proposedServices: [NSSharingService]) -> [NSSharingService] {
-		let filteredServices = proposedServices.filter { $0.menuItemTitle != "NetNewsWire" }
-		return filteredServices + SharingServicePickerDelegate.customSharingServices(for: items)
+
+		MainActor.assumeIsolated {
+			let filteredServices = proposedServices.filter { $0.menuItemTitle != "NetNewsWire" }
+			return filteredServices + SharingServicePickerDelegate.customSharingServices(for: items)
+		}
 	}
 
 	func sharingServicePicker(_ sharingServicePicker: NSSharingServicePicker, delegateFor sharingService: NSSharingService) -> NSSharingServiceDelegate? {
 		return sharingServiceDelegate
 	}
 
-	static func customSharingServices(for items: [Any]) -> [NSSharingService] {
+	@MainActor static func customSharingServices(for items: [Any]) -> [NSSharingService] {
 		let customServices: [SendToCommand] = [SendToMarsEditCommand(), SendToMicroBlogCommand()]
 
 		return customServices.compactMap { (sendToCommand) -> NSSharingService? in
diff --git a/Shared/ExtensionPoints/SendToMarsEditCommand.swift b/Shared/ExtensionPoints/SendToMarsEditCommand.swift
index 61752583c..675fd6355 100644
--- a/Shared/ExtensionPoints/SendToMarsEditCommand.swift
+++ b/Shared/ExtensionPoints/SendToMarsEditCommand.swift
@@ -11,7 +11,7 @@ import Articles
 import Core
 import AppKitExtras
 
-final class SendToMarsEditCommand: SendToCommand {
+@MainActor final class SendToMarsEditCommand: SendToCommand {
 
 	let title = "MarsEdit"
 	let image: RSImage? = AppAssets.marsEditIcon
@@ -44,9 +44,9 @@ final class SendToMarsEditCommand: SendToCommand {
 	}
 }
 
-private extension SendToMarsEditCommand {
+@MainActor private extension SendToMarsEditCommand {
 
-	@MainActor func send(_ article: Article, to app: UserApp) {
+	func send(_ article: Article, to app: UserApp) {
 
 		// App has already been launched.
 
diff --git a/Shared/ExtensionPoints/SendToMicroBlogCommand.swift b/Shared/ExtensionPoints/SendToMicroBlogCommand.swift
index 4de3e8447..235e4d6f6 100644
--- a/Shared/ExtensionPoints/SendToMicroBlogCommand.swift
+++ b/Shared/ExtensionPoints/SendToMicroBlogCommand.swift
@@ -13,7 +13,7 @@ import AppKitExtras
 
 // Not undoable.
 
-final class SendToMicroBlogCommand: SendToCommand {
+@MainActor final class SendToMicroBlogCommand: SendToCommand {
 
 	let title = "Micro.blog"
 	let image: RSImage? = AppAssets.microblogIcon
@@ -30,7 +30,7 @@ final class SendToMicroBlogCommand: SendToCommand {
 		return true
 	}
 	
-	@MainActor func sendObject(_ object: Any?, selectedText: String?) {
+	func sendObject(_ object: Any?, selectedText: String?) {
 
 		guard canSendObject(object, selectedText: selectedText) else {
 			return